Analysis Of Parameters Research Articles

Structural implementation of recycled lump prepared from waste concrete after elevated temperatures: Mechanical and environmental performances

To find a sustainable treatment for construction and demolition waste, the utilization of recycled lump (RL) prepared from waste concrete after elevated temperatures as coarse aggregate in concrete was investigated. The mechanical and environmental properties of recycled lump concrete (RLC) and reinforced recycled lump concrete (RRLC) were discussed with three RL replacement ratios and five treatment temperatures. The results show that increasing the RL replacement ratio would reduce the slump, and axial compressive performance of RLC, resulting from the presence of old adhered mortar on RL. The treatment of elevated temperature for RLC would improve the adverse effect of increasing the RL replacement ratio, resulting from the decreasing amount of old adhered mortar and interfacial transition zone on RL. The prediction formulas for the mechanical model of RLC were proposed while the design method for the axial compressive strength for RRLC was modified against the existing standard to conduct the full-range parametric analysis. The environment assessment indicates that the sustainable utilization of RL as coarse aggregate could reduce the environmental impact and global warming from concrete production whilst the RL prepared from waste concrete after 400oC treatment is an appreciated option for the production of RLC and RRLC products from a mechanical and environmental perspective. In addition, the increase in external diameter would remarkably dwindle the environmental impact caused by the utilization of RL in structural members.

Experimental and numerical investigation on seismic performance of SFRC shear walls with CFRP bars

In order to investigate the seismic performance of steel fiber reinforced concrete (SFRC) shear walls with CFRP bars, quasi-static tests were conducted on six full-scale shear walls with a shear span ratio of 2.0, including one steel bars reinforced ordinary concrete (RC) shear wall, one CFRP bars reinforced ordinary concrete (CRC) shear wall and four CFRP bars reinforced SFRC (CSFRC) shear walls. The variables included steel fiber volume fraction (SFVF), axial load ratio and concrete strength grade. The experimental results showed increasing the SFVF could significantly decrease the concrete damage level and improve repairability. Meanwhile, the bearing capacity, ductility, and energy dissipation capacity all improved, and the stiffness degradation slowed. Compared to RC shear wall, the peak load of the CSFRC shear wall with SFVFs of 0 %, 0.75 % and 1.5 % increased by 16.36 %, 30.06 % and 46.01 %, respectively. The residual drift ratio decreased by 54.75 %, 61.61 %, and 52.98 % at 2.2 % drift ratio, respectively. Compared to CRC shear wall, the cumulative energy dissipation of the CSFRC shear wall with SFVFs of 0.75 % and 1.5 % increased by 39.54 % and 94.10 %; and the ductility increased by 5.12 % and 18.06 %, respectively. These improvements indicated that applying SFRC with SFVFs of 0.75 % and 1.5 % to shear walls reinforced with CFRP bars could effectively improve the seismic performance and compensate for the shortcomings of resilient shear walls. In addition, increasing the axial load ratio improved the bearing capacity, but decreased deformation capacity and accelerated stiffness degradation. An increase in concrete strength significantly improved the bearing capacity, stiffness and energy dissipation but reduced ductility. Meanwhile, the stability of lateral loads at large drift ratios weakened. Additionally, a detailed finite element model (FEM) was established using DIANA and the accuracy was verified by comparing the simulation and experimental results. Subsequently, parametric analyses were carried out to study the effects of shear span ratio, CFRP bar ratio, and wall thickness on the seismic behaviour of CSFRC shear walls.

Experimental and parametric study on friction-type high-strength bolted connections between steel frames and cross-laminated timber infill walls

Timber-steel hybrid structural systems provide a prospective solution for utilizing timber in multi-storey and high-rise buildings. The system of steel frame with infilled cross-laminated timber (CLT) shear walls is an effective hybrid timber-steel one. In the design of this kind of hybrid system, the connections between CLT walls and steel frame beams are key issues, because they have great impacts on the distribution of lateral forces in structures. In this paper, a friction-type high-strength bolted connection (FHBC) between CLT walls and steel frame beams is proposed. To investigate the performance of the proposed FHBC, experiments were conducted on the FHBCs fabricated with three- and five-ply CLT. The mechanical behaviors of the connections were evaluated. The pretension loss in the tested FHBCs with three-layer CLT is less than 15 % within a displacement of 10 mm. Besides, enhancement of axial force in the high-strength bolt was observed in the five-layer connections during the loading procedure. Theoretical analysis was performed to provide recommendations on the initial pretension force of FHBCs. Furthermore, a solid element-based numerical model was developed and validated by the experimental results. The parametric analysis was conducted to investigate the effect of friction coefficient and initial pretension force on the mechanical behaviors of FHBC. The numerical simulation results show that the greater the initial pretension force is, the bigger the slip activation force and ultimate load-carrying capacity of the FHBC are. When the friction coefficient between CLT wall and steel beam is greater than 0.4, the ultimate load-carrying capacity does not increase much. The experimental and numerical results demonstrate that such connections can provide sufficient stiffness, strength, and ductility to transfer the shear force between the CLT shear walls and the steel frame beams.

Novel THAI well arrangements for improving heavy oil recovery rate in comparison to that achievable in the conventional THAI in situ combustion technology

The toe-to-heel air injection (THAI) is an environmentally friendly process for in situ upgrading of heavy oils and bitumen via in situ combustion (ISC). Unlike the conventional ISC that uses a vertical producer, the THAI process uses a horizontal producer (HP) well to produce the upgraded oil to the surface. Recent field data has shown that the THAI process is a relatively low-oil-production-rate technology. These considerations call for innovative solutions so that the oil production rate is improved, whilst propagating a stable, efficient, and safe combustion front. Consequently, this work has provided those solutions. Through numerical reservoir simulations, using CMG STARS, five completely new THAI well configurations, which have been labeled A01, A02, A03, A04, and A05, have been developed and studied, and their performances are compared against that of the conventional THAI process which has wells arranged in a classic SLD pattern (i.e. the best-performing conventional THAI process) and against each other. The THAI arrangements A02-A04, however, assume a horizontal air injection well, which currently is not used in field practice but may be developed in the future. In field practice, THAI is applied in a line drive configuration starting up-dip and going down on the structure whilst taking advantage of the contribution provided by the drainage due to gravity; the expansion is made one way only (by drilling new patterns in one direction only). For this reason, the classic SLD pattern refers to the case where the dip of the reservoir is significant (>2-3 degrees). However, when the dip of the reservoir is not significant (“flat” reservoirs) there is a possibility to expand the process in both opposing directions. This is the case dealt with in this work. All configurations A01-A05 assume expansion of the THAI commercial operation in both directions. Selection criteria have been developed and used to determine the two best performing processes. For example, in terms of long-term stability, safety, and efficiency of the combustion process, a process named model A01 is the best, as it achieved 99.8% oxygen utilization when compared with any other model. It also achieves oil recovery, due to two years of combustion only, of 30.78% OOIP, which is greater than that in the base case model. Overall, based on the weighted selection criteria, which are developed from the deepest analyses of the quantitative 1-dimensional time-dependent parameters and from thorough analyses of the qualitative 2-dimensional profiles of temperature, the combustion zone in the form of oxygen mole fraction, and the oil-flow dynamics inside the reservoir in the form of oil saturation, then model A01 is the best and is followed by model A03. The overall performance of each of these two novel methods outweighs that of the conventional THAI process. However, model A03 uses a horizontal well for injection, which is not current field practice. Therefore, future developmental work should concentrate on the novel method A01 for upgrading and recovery of heavy oils and bitumen, especially since this is low-carbon, efficient, wastewater-free, and provides upgrading inside the reservoir and hence it has a low surface footprint.

Choline-deficient high-fat diet-induced MASH in Göttingen Minipigs: Characterisation and effects of a chow reversal period.

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) is increasing, and translational animal models are needed to develop novel treatments for this disease. The physiology and metabolism of pigs have a relatively high resemblance to humans, and the present study aimed to characterise choline-deficient, and high-fat diet (CDAHFD) fed Göttingen Minipigs as a novel animal model of MASLD/MASH. Göttingen Minipigs were fed CDAHFD for up to 5 months, and the phenotype was investigated by analysis of plasma parameters and repeated collection of liver biopsies. Furthermore, changes in hepatic gene expression during the experiment were explored by RNA sequencing. For a subset of the minipigs, the diet was changed from CDAHFD back to chow to investigate if the liver pathology was reversible. Göttingen Minipigs on CDAHFD gained bodyweight, and plasma levels of cholesterol, AST, ALT, ALP and GGT were increased. CDAHFD-fed minipigs developed hepatic steatosis, inflammation, and fibrosis, which in 5 of 16 animals progressed to cirrhosis. During an 11-week chow reversal period, steatosis regressed while fibrosis persisted. Regarding inflammation, the findings were less clear, depending on the type of readout. MASH Human Proximity Scoring (combined evaluation of transcriptional, phenotypic and histopathological parameters) showed that CDAHFD-fed Göttingen Minipigs resemble human MASLD/MASH better than most rodent models. In conclusion, CDAHFD-fed minipigs develop a MASH-like phenotype which in several aspects resemble the changes observed in human patients with MASLD/MASH. Furthermore, repeated collection of liver biopsies allow detailed characterisation of histopathological changes over time in individual animals.

The Optimal Measurement Period of Actigraphy for Circadian Rhythm in Relation to Adiposity: A Retrospective Case-Control Study

BackgroundThis study focused on the relationship between adiposity and Rest-Activity Rhythms (RAR), utilizing both parametric cosine-based models and non-parametric algorithms. The emphasis was on the impact of varying measurement periods (7 to 28 days) on this relationship. MethodsWe retrieved actigraphy data from two datasets, encompassing a diverse cohort recruited from an obesity outpatient clinic and a workplace health promotion program. Participants were required to wear a research-grade wrist actigraphy device continuously for a minimum of four weeks. The final dataset included 115 individuals (mean age 40.7 ± 9.5 years, 51% female). We employed both parametric and non-parametric methods to quantify RAR using six standard variables. Additionally, the study evaluated the correlations between three key adiposity indices — Body Mass Index (BMI), Visceral Adipose Tissue (VAT) area, and Body Fat Percentage (BF%) — and circadian rhythm indicators, controlling for factors like physical activity, age, and gender. ResultsThe obesity group displayed a significantly lower relative amplitude (RA) as per non-parametric algorithm findings, with a decreased amplitude noted in the parametric algorithm analysis, in comparison to the overweight and control groups. The relationship between circadian rhythm indicators and adiposity metrics over 7- to 28-day periods was examined. A notable negative correlation was observed between RA and both BMI and VAT, while correlation coefficients between adiposity indicators and non-parametric circadian parameters increased with extended durations of actigraphy data. Specifically, RA over a 28-day period was significantly correlated with BF%, a trend not seen in the 7-day measurement (p = 0.094) in multivariate linear regression. The strength of the correlation between BF% and 28-day RA was more pronounced than that in the 7-day period (p = 0.044). However, replacing RA with amplitude as per parametric cosinor fitting yielded no significant correlations for any of the measurement periods. ConclusionThe study concludes that a 28-day measurement period more effectively captures the link between disrupted circadian rhythms and adiposity. Non-parametric algorithms, in particular, were more effective in characterizing disrupted circadian rhythms, especially when extending the measurement period beyond the standard 7 days.

Identification of Multi-Parameter Fluid in Igneous Rock Reservoir Logging—A Case Study of PL9-1 in Bohai Oilfield

Since the “13th Five-Year Plan”, the exploration of large-scale structural oil and gas reservoirs in the Bohai oilfield has become more complex, and the exploration of igneous oil and gas reservoirs has become the focus of current attention. At present, igneous rock reservoir fluid identification methods are mainly based on the evaluation method of logging single parameter construction, which is primarily a qualitative identification due to lithology, physical property, and engineering factors. Accurate acquisition of interference logging data, and multi-parameter coupling and recording coupling methods are few, lacking systematic and comprehensive evaluation and analysis of logging data. Since conventional logging data in the study area have difficulty accurately and quickly identifying reservoir fluid properties, a systematic analysis was conducted of three factors: lithology, physical properties, and engineering, as well as a variety of logging parameters (gas measurement, three-dimensional quantitative fluorescence, geochemical, FLAIR, etc.) that can reflect fluid properties were integrated. Based on parameter sensitivity analysis, the quantitative characterization index FI of multi-parameter coupling fluid identification was established using the data from testing, sampling, and laboratory testing to develop the identification standard. The sensitivity analysis and optimization of characteristic parameters were carried out by integrating the data reflecting fluid properties such as gas surveys, geochemical data, and related logging data. Combined with gas logging-derived parameters and improved engineering parameters (the value of alkanes released by rock cracking per unit volume Cadjust, C1 abnormal multiple values, three-dimensional quantitative fluorescence correlation factor N), the fluid properties were identified, evaluation factors were constructed based on factor analysis, and fluid identification interactive charts were established. By analyzing test wells in the PL9-1 well area, the results of comparison test data are more reliable. Compared with conventional methods, this method reduces the dependence of a single parameter by synthesizing multiple parameters and reduces the influence of lithology, physical properties, and engineering parameters on fluid identification. It is more reasonable and practical. It can accurately and quickly identify the fluid properties of igneous rock reservoirs in the study area. It has a guiding significance for improving the accurate evaluation of logging data and increasing exploration benefits.

Choroidal vascularity features of fundus tessellation in adults with high myopia

BackgroundTo investigate alterations in choroidal vascularity index among highly myopic adults with fundus tessellation, utilizing optical coherence tomography.MethodsTotal of 143 highly myopic adults (234 eyes) with fundus tessellation were collected in this cross-sectional study, which was stratified into different lesion groups based on the novel tessellated fundus classification. Subfoveal choroidal thickness (SFCT), choroidal luminal area (LA), stromal area (SA), total choroidal area (TCA), and choroidal vascularity index (CVI) were analyzed utilizing optical coherence tomography (OCT) with enhanced depth imaging (EDI) mode, enabling precise quantification of these parameters.ResultsComparison analysis demonstrated notable distinctions in spherical equivalent (SE), axial length (AL), and SFCT across the four tessellation grades (p < 0.001). Analysis of the choroidal vascularity parameters, including LA, TCA, and CVI, demonstrated notable disparities across the four groups (p < 0.001), while no significant variations were observed in SA when comparing Grade 1 versus Grade 2, as well as Grade 2 versus Grade 3 (p > 0.05). Logistic regression analyses illustrated that the higher grade of tessellated exhibited a positive association with AL (OR = 1.701, p = 0.027), while negatively associated with SFCT (OR = 0.416, p = 0.007), LA (OR = 0.438, p = 0.010) and CVI (OR = 0.529, p = 0.004). Multiple regression analyses demonstrated a significant negative association between CVI and both SE and AL after adjusting for age, while positively associated with SFCT (p < 0.05).ConclusionSubtle choroidal vascularity changes may have a meaningful contribution to the development and progression of fundus tessellation. CVI and LA dramatically decreased during the early stages of tessellation development and maintained a relatively stable status when in the severe tessellated grades.

Equilibrium Interaction Strategies for Integrated Energy System Incorporating Demand-Side Management Based on Stackelberg Game Approach

This paper analyzes the balanced interaction strategy of an integrated energy system (IES) operator and an industrial user in the operation process of the IES under the demand-side management (DSM) based on game theory. Firstly, we establish an electric–thermal IES, which includes a power grid, a heat grid and a natural gas grid. Secondly, a two-stage Stackelberg dynamic game model is proposed to describe the game behavior of IES operators and industrial users in the process of participating in DSM. The interactions between the IES operator (leader) and the user (follower) are formulated into a one-leader–one-follower Stackelberg game, where optimization problems are formed for each player to help select the optimal strategy. A pricing function is adopted for regulating time-of-use (TOU), which acts as a coordinator, inducing users to join the game. Then, for the complex two-stage dynamic game model established, the lower user-side constraint optimization problem is replaced by its KKT condition, so that the two-stage hierarchical optimization problem is transformed into a single-stage mixed-integer nonlinear optimization model, and the branch-and-bound method is introduced to solve it. Finally, the equilibrium strategies and income values of both sides of the game are obtained through a case simulation, and the dynamic equilibrium strategy curves under different capacity configurations are obtained through the sensitivity analysis of key parameters. The equilibrium income of the IES is USD 93.859, while the equilibrium income of industrial users in the park is USD 92.720. The simulation results show that the proposed method and model are effective.

Prediction of Motor Recovery Using Diffusion Tensor Imaging and Regional Cerebral Blood Flow in Postoperative Brain Tumors.

To determine whether diffusion tensor image (DTI) parameters and regional cerebral blood flow (rCBF) serve to preoperatively predict postoperative motor outcomes in patients with brain tumors. We included 81 patients with brain tumors who underwent surgical treatment. Motor function was assessed using the manual muscle test in the upper and lower limbs at admission and discharge. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and their ratios (rFA, rMD, rAD, and rRD) were measured at the corona radiata, internal capsule, and cerebral peduncle of the corticospinal tract (CST). In addition, DTI and single photon emission computed tomography (SPECT) were synthesized to measure rCBF at the CST. Both DTI parameters and rCBF at the CST in the preoperative motor weakness group significantly differed from those of the preoperative normal function group. rFA at the cerebral peduncle and the internal capsule was considerably higher in those showing postoperative motor recovery than in those postoperative unchanged or with deteriorated motor function (P < 0.05). Moreover, there was significantly lower rMD and rRD at the internal capsule in the motor recovery group (P < 0.05, P < 0.01).Furthermore, rCBF was higher at all the cerebral peduncle, internal capsule, and corona radiate in the motor recovery group than in the unchanged and deteriorated motor function group (P < 0.05, P < 0.01, P < 0.01). The analysis of DTI parameters and rCBF is useful in predicting postoperative motor outcomes in patients with brain tumors.

Advancement in transformer fault diagnosis technology

The transformer plays a critical role in maintaining the stability and smooth operation of the entire power system, particularly in power transmission and distribution. The paper begins by providing an overview of traditional fault diagnosis methods for transformers, including dissolved gas analysis and vibration analysis techniques, elucidating their developmental trajectory. Building upon these traditional methods, numerous researchers have aimed to enhance and optimize them through intelligent technologies such as neural networks, machine learning, and support vector machines. These researchers have addressed common issues in traditional fault diagnosis methods, such as the low correlation between characteristic parameters and faults, ambiguous fault descriptions, and the complexity of feature analysis. However, due to the complexity of transformer structures and the uncertainties in operating environments, the collection and analysis of characteristic parameters becomes highly intricate. Researchers have further refined algorithms and feature values based on intelligent diagnostic algorithms for transformers. The goal is to improve diagnostic speed, mitigate the impact of measurement noise, and further advance the adaptability of artificial intelligence technology in the field of transformers. On the other hand, the excellent multi-parameter analysis capability of artificial intelligence technology is more suitable for transformer diagnostic techniques that involve the fusion of multiple information sources. Through the powerful data acquisition, processing, and decision-making capabilities provided by intelligent algorithms, it can comprehensively analyze non-electrical parameters such as oil and gas characteristics, vibration signals, temperature, along with electrical parameters like short-circuit reactance and load ratio. Moreover, it can automatically analyze the inherent relationship between faults and characteristic quantities and provide decision-making suggestions. This technique plays a pivotal role in ensuring transformer safety and power network security, emerging as a prominent direction in transformer fault diagnosis research.

An integrated approach to analysis and assessment of condition parameters of the surface layer of backup roll bodies of a continuous broad-strip hot rolling mill

An integrated approach to analysis and assessment of condition parameters of the surface layer of backup roll bodies of a continuous broad-strip hot rolling mill

Slope Stability Analysis of Rockfill Embankments Considering Stress-Dependent Spatial Variability in Friction Angle of Granular Materials

Slope stability is a major safety concern of rockfill embankments. Since rockfills are incohesive materials, only friction angle is considered as a shear strength parameter in the slope stability analysis of rockfill embankments. Recently, it was found that confining pressure can significantly affect the mean value and variance of the friction angle of rockfills. Since the confining pressure spatially varies within a rockfill embankment, the effect of stress-dependent spatial variability in the friction angle of rockfills should be investigated for slope stability evaluation of rockfill embankments. In the framework of the Limit Equilibrium Method (LEM), an approach is proposed for the slope stability analysis of rockfill embankments considering the stress-dependent spatial variability in the friction angle. The safety factors of slope stability are computed with variable values of the friction angle at the bases of slices which are determined by the stress-dependent mean value and variance of the friction angle of rockfills. The slope stability of a homogeneous rockfill embankment is analyzed to illustrate the proposed approach, and a parametric analysis is carried out to explore the effect of variation in the parameters of the variance function of friction angle on slope stability. The illustrative example demonstrates that the stress-dependent spatial variability of friction angle along the slip surface is obvious and is affected by the location of the slip surface and the loading condition. The effects of the stress-dependent spatial variability of the friction angle on the slope stability of high rockfill embankments should be considered.

Interplay of size and magnetic effects in electrocatalytic water oxidation activity of sub-10 nm NiOx supported porous hard-carbons.

This report describes a systematic approach for precise engineering of a catalyst-metal oxide interface through combining complementary approaches of chemical vapor deposition and atomic layer deposition. Specifically, Chemical Vapor Deposition (CVD) fabricated nanostructured hard-carbon framework (NCF) is employed as synergistic support for precise deposition of NiOx particles through Atomic Layer Deposition (ALD). The three variants of NCF-NiOx system (dimensions ranging from 3-12 nm, surface coverage ranging from 0.14% to 2%) achieved exhibit unique electrocatalytic water oxidation activities, that are further strongly influenced by an external magnetic field (Hext). This confluence of size engineering and associated magnetic field effects interplay to produce the largest lowering in Rct at Hext = 200 mT. A comprehensive analysis of electrocatalytic parameters including the Tafel slope and double layer capacitance establishes further insights on co-relation of size effect and magnetic properties to understand the role of nanocarbon supported transition metal oxides in water electrolysis.

Artificial intelligence-based assessment of leg axis parameters shows excellent agreement with human raters: A systematic review and meta-analysis.

The aim of this study was to conduct a systematic review and meta-analysis on the reliability and applicability of artificial intelligence (AI)-based analysis of leg axis parameters. We hypothesized that AI-based leg axis measurements would be less time-consuming and as accurate as those performed by human raters. The study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO). PubMed, Epistemonikos, and Web of Science were searched up to 24 February2024, using a BOOLEAN search strategy. Titles and abstracts of identified records were screened through a stepwise process. Data extraction and quality assessment of the included papers were followed by a frequentist meta-analysis employing a common effect/random effects model with inverse variance and the Sidik-Jonkman heterogeneity estimator. A total of 13 studies encompassing 3192 patients were included in this meta-analysis. All studies compared AI-based leg axis measurements on long-leg radiographs (LLR) with those performed by human raters. The parameters hip knee ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), and joint-line convergence angle (JLCA) showed excellent agreement between AI and human raters. The AI system was approximately 3 min faster in reading standing long-leg anteroposterior radiographs (LLRs) compared with human raters. AI-based assessment of leg axis parameters is an efficient, accurate, and time-saving procedure. The quality of AI-based assessment of the investigated parameters does not appear to be affected by the presence of implants or pathological conditions. Level I.

A simplified approach to modeling temperature dynamics in photovoltaic systems – Validation, case studies, and parametric analysis

This paper presents a simplified theoretical model for analyzing the temperature dynamics of photovoltaic (PV) modules. The model is built on an energy balance approach, considering solar irradiation as the primary energy input. It accounts for the conversion of solar power into electricity and the storage of thermal energy within the PV module, which subsequently increases the PV temperature leading to decay in its electrical efficiency. Heat loss from the top and bottom surfaces of the module, with variations for cooling techniques, is also included. The model is validated against three different experimental studies, demonstrating good agreement with the experimental temperature variations, with a maximum discrepancy ranging from 4 % to 16 %. This simplified model is then applied to two case studies: one representing typical daytime conditions and another simulating cold weather events. By comparing the PV temperature dynamics between the model and the experimental data, it is shown that the model accurately captures the dynamic response of the PV temperatures to changes in solar irradiation and ambient temperatures. Moreover, a parametric analysis is conducted to investigate the effects of key parameters on PV temperature and efficiency. Higher cooling rates from the bottom surface significantly boost electric power output, aligning closely with solar irradiance variations. Enhanced upper surface cooling, through increased convection, reduces PV temperature and thereby improves electric efficiency and power production. The PV temperature increases quasi-linearly with ambient temperature, especially at lower wind speeds, and decreases with higher wind speeds, eventually stabilizing at high values. Additionally, both ambient temperature and solar irradiance contribute to rising PV temperatures, with ambient temperature having a slightly greater effect. These findings underscore the critical role of cooling techniques in optimizing PV performance amidst varying environmental conditions.

Microstructural study with enhanced dielectric and magnetic properties of Cu1-xCdxFe2O4 nanoparticles prepared at low-temperature green-synthesized technique

The green elaboration tool has taken much consideration due to its consistent and economical ways of producing pure and regular dispersed NPs. The preparation tool is a simple, environmentally friendly, and cost-effective method that does not use toxic chemicals. Therefore, the biological mechanisms themselves act as a reducing agent that prevents, on the surface of nanoparticles, the adsorption of chemical agents. Therefore, we focus in this work on the bio-synthesizes and the characterization (crystallographic, magnetic, transport, and dielectric study) of Cu1-xCdxFe2O4(x = 0.0, 0.3 and x = 0.5) spinel ferrites. X-ray diffraction, transmission electron microscopy (TEM), and photoelectron spectroscopy (XRD and XPS) have been employed to study crystallographic characteristics and chemical bond formation. Surface parameters analysis was conducted using BET isotherms and validated the decreases in specific surface area in the substitution sample. The electrical investigation proves the semiconductor behavior, and the thermal activation are dominated by the small polaron hopping mechanism in the nano-ferrites Cu1-xCdxFe2O4. In addition, the prepared NPS exhibits low dielectric losses. Using the ZFC-FC and M(H) measurement techniques, important modifications in the magnetic behaviors have been detected in the elaborated nanoparticles. Accordingly, the substitution of Cu1-xCdxFe2O4 leads to transitions from ferromagnetic to superparamagnetic behaviors, the increase of the magnetic saturation, and decreased magnetic anisotropy has been shown in Cu0·7Cd0·3Fe2O4 spinel structure.

Towards the use of archaeomagnetism as an archaeological dating tool for South America

Dating archaeological materials is essential to understand time and rate of changes in different civilizations. For this purpose, different dating methods are used in several materials, including organic remains, sediments, and ceramics. Archaeomagnetic dating is a developing dating tool that has been improving rapidly due to the advances in geomagnetic model curves. The premise of this method is to compare the inclination, declination, and intensity of the geomagnetic field recorded by burnt archaeological materials (i.e., bricks, kilns, burned floors, pit ovens, soils, ceramics, slags), with mathematical models that describe the evolution of the Earth's magnetic field. Different regional geomagnetic models have been built based on local data that allow the application of this dating method, whereas for regions where regional models are lacking, global geomagnetic models are used. In any case, it is essential to assess the intrinsic uncertainties of geomagnetic models to properly evaluate the feasibility of the archaeomagnetic dating. In this context, this work evaluated global geomagnetic models for South America over the last 2000 years, to select the most appropriate statistically for dating purposes. Based on Casas and Tema (2019), a thorough assessment of the age uncertainties of the models was carried out. The statistical analyses of the magnetic parameters of the selected models regarding high-quality data were integrated to the intersection analyses of different magnetic parameters. From this result, this study suggests a geomagnetic multi-model approach as the best configuration for archaeomagnetic dating for South America.

Study on the instability mechanism and control technology of narrow coal pillar in double-roadway layout of Changping mine

To address the issue of roadway support failure in narrow coal pillars under dual-lane layout, this study takes the 4309 working face of Changping Coal Mine as the engineering background and employs theoretical calculations, numerical simulations, and on-site monitoring to investigate the instability mechanisms of narrow coal pillars under dual-lane conditions and to optimize technical solutions. The results indicate that the internal stress distribution within the coal pillar is influenced by the advanced support stress, and as the working face advances, the gradually increasing advanced support pressure causes the vertical stress peak within the coal pillar to shift away from the goaf area. Computational analysis reveals that the vertical stress in the top region of a 6 m narrow coal pillar is 38% higher than that in the bottom region, with an average stress of 16 MPa in the coal pillar. The asymmetric high-level stress concentration within the coal pillar significantly affects its stability. A UDEC (Universal Distinct Element Code) model was established to compare four simulation schemes with cut-off angles of 0°, 5°, 10°, and 15°. Based on the analysis of damage parameters and fracture distribution in the narrow coal pillar roadway, it was concluded that the stability is best when the cut-off angle is 10°. The dense drilling cut-off unloading technology was applied to the 4309 working face of the Changping Mine based on the aforementioned research. On-site monitoring results show that the relative deformation of the roof and bottom plates and the two sides of the test section were controlled within 267 mm and 198 mm, respectively, effectively resolving the deformation and instability issues of the narrow coal pillars.

Optimization Analysis of Various Parameters Based on Response Surface Methodology for Enhancing NOx Catalytic Reduction Performance of Urea Selective Catalytic Reduction on Cu-ZSM-13 Catalyst

Optimization Analysis of Various Parameters Based on Response Surface Methodology for Enhancing NOx Catalytic Reduction Performance of Urea Selective Catalytic Reduction on Cu-ZSM-13 Catalyst